Hello, I am working on a John Deere 675b w/a Yanmar diesel engine. When you are using it at full throttle, it will intermittently slow down to an idle speed, then die. After you let it sit for about half a minute, it will start back up and you can limp it back to the shop. I have already changed the fuel filter and bled the fuel system. What are your thoughts? Thanks, Jim
When it dies, open up a bleeder on the pump or close to it. If it sucks air, then next time work your way back toward the tank. Eventually you'll find something. If it leaks fuel, you could put a pressure gauge on it and see if that's up to snuff when it dies/limps.
I put a fuel pressure guage in the fuel line after the electric pump with a T fitting and I was only seeing about 1 1/2 psi pressure. The pressure stayed consistent whether the machine was on or off. Does that seem too low? Jim
Maybe a little low? but I don't have a spec to know so I'm just a guessin. How's the volume? and does the pressure and/or volume improve if you disconnect the inlet to the fuel pump and put it in a container of fuel? Or if you have a vacuum gauge you could tee that in before the fuel pump and see if it pulls an unusual vacuum when it dies/limps. Or you could blow out the line back into the tank, or if the fuel supply coming out of the tank has a larger threaded fitting, it probably removes to let you replace the gunked up and collapsed inlet screen. You might be that lucky.
Be most suspicious of the electric fuel pump. They can pump and make noise, but not have any pressure. Also look at the fuel tank and see if it shows signs of being sucked in. Could be a bad fuel cap. We have also seen the plastic fuel tank come up against the fuel pickup tube and starve the engine of fuel. We cut the tube off at a 45 degree angle at the bottom to solve that. Brian